Multi-spiral satellite antenna



1964 M. G. CHATELAIN 3,152,330

MULTISPIRAL SATELLITE ANTENNA Filed March 27, 1961 INVENTOR.

MAURICE G. CHATELAI N United States Patent 3,152,330 MULTI-SPIRAL SATELLITE ANTENNA Maurice G. Chatelain, San Diego, Calif., assignor to The Ryan Aeronautical Co., San Diego, Calif. Filed Mar. 27, 1961, Ser. No. 98,399 6 Claims. (Cl. 343705) The present invention relates generally to antennas and more particularly to a multi-spiral antenna.

In the art of space communications, various types of antennas have been utilized but are normally of omnidirectional type and subject to considerable losses of efficiency due to the small amount of energy which is directed toward ground based receivers. A directive antenna is desirable, but the stabilization of a satellite mounted antenna is complex and costly. Also, since the cost of placing a satellite in orbit is high, it is necessary to utilize any satellite to the maximum, in whch case the antenna must be capable of handling signals over a large frequency bandwidth.

For maximum efficiency, the antenna must be of reasonable size in its operating configuration, yet be of minimum weight and small collapsed dimensions to fit inside a launching vehicle.

The primary object of this invention therefore, is to provide an antenna of flexible material which is inflatable to an operable configuration and has a plurality of wide bandwidth elements which can be used singly or in conjunction to control directivity.

Another object of this invention is to provide an antenna having concentric, inflatable shells on which antenna elements are carried in stacked arrays, each including active, reflector and director elements.

Another object of this invention is to provide an antenna which is of minimum weight and can be stored in a very small space when collapsed, yet when inflated forms a self-aligning, rigid structure.

Finally, it is an object to provide a multi-spiral antenna of the aforementioned character which is simple and convenient to construct and which will give generally efficient and durable service.

With these and other objects definitely in view, this invention consists in the novel construction, combination and arrangement of elements and portions, as will be hereinafter fully described in the specification, particularly pointed out in the claims, and illustrated in the drawing which forms a material part of this disclosure, and in which:

FIGURE 1 is a side elevation View of the antenna, partially cut away; and

FIGURE 2 is a fragmentary sectional View taken on the line 22 of FIGURE 1.

Similar characters of reference indicate similar or identical elements and portions throughout the specification and throughout the views of the drawing.

The antenna in its basic form as illustrated comprises three concentric shells, an inner shell 10, an intermediate shell 12 and an outer shell 14. Each shell is spherical and made from thin, flexible material such as plastic, the shells being held in concentric spaced relation by flexible interconnecting webs 16. The entire structure can be folded into a small package and is easily inflated to its operating configuration, the shells being collectively or individually inflated by any suitable means, such as compressed gas, sublimating powders, or the like.

On the inner shell 10 are a plurality of conductive, spiral dipole, reflector elements 18 spaced in a geometrical pattern, the elements being applied directly to the plastic shell by painting, printing, or otherwise depositing metal on the material in the required spiral configuration. On the immediate shell 12 are spiral dipole driven elements 20 and on the outer shell 14 are spiral dipole, director elements 22, all of the spiral dipole elements being similar and applied in the same manner. The elements are aligned in radially stacked arrays, each containing a reflector element, a driven element and a director element, as illustrated in FIGURE 2 and in the cutaway portion of FIGURE 1. The spherical shells are held in the proper orientation when inflated by the webs 16, to insure accurate alignment of the individual arrays of elements.

For control of directivity, one pole of each driven element 20 is connected to a switch unit 24, while the other pole is connected to a common ground plane 26. The switch unit 24 is of any suitable type, mechanical, electronic, or otherwise, which is capable of interconnecting pairs or groups of the antenna elements to receive or transmit signals in specific directions. Various types of receiving and transmitting apparatus can be coupled to the antenna through the switch unit 24, which can be operated by sequencing means or command signals, according to requirements.

The spiral dipoles may be of Archimedes spiral type for maximum directivity, or of logarithmic spiral type for maximum bandwidth which is also affected by the spacing between the elements. Additional directional limitation can be achieved by adding further parasitic elements to the arrays. This can be accomplished by using additional spherical outer shell carrying the other director elements, so that the antenna contains four or five concentric spheres.

The antenna is extremely simple in construction and even a very large assembly may be folded into a compact, light weight package for launching into orbit, the balloon-like structure requiring no internal bracing frame or struts. The spiral dipoles are very thin and fold with the flexible material of the shells without damage. If necessary, even the connections to the switch unit may be in the form of printed circuits on the plastic shells and webs. The spiral type of antenna is capable of handling a wide frequency bandwidth and thus allows the antenna assembly to be used with many different types of equipment, instead of requiring an individual antenna for each particular frequency. Also by means of the switch arrangement, the most effective arrays of elements can be utilized to direct the signals where required, regardless of the orientation of the antenna satel lite itself in space. The operation of this invention will be clearly comprehended from a consideration of the foregoing description of the mechanical detail thereof, taken in connection with the drawing and the above recited objects. It will be obvious that all said objects are amply achieved by this invention.

It is understood that minor variation from the form of the invention disclosed herein may be made without departure from the spirit and scope of the invention, and that the specification and drawing are to be considered as merely illustrative rather than limiting.

I claim:

1. An antenna, comprising:

a plurality of concentrically spaced, hollow bodies;

each of said bodies having a plurality of conductive antenna elements thereon;

said bodies being relatively fixedly disposed so that said elements are aligned in radially stacked arrays, each including a reflector element, a driven element and at least one director element.

2. An antenna according to claim 1 and including switch means connected to said driven elements and being operable to interconnect selected elements.

3. An antenna, comprising:

a plurality of inflatable, substantially spherical shells 6 interconnected in fixed concentrically spaced relation;

each of said shells having a plurality of conductive antenna elements thereon;

said elements being aligned in radially stacked arrays each including a reflector element, a driven element and at least one director element.

4. An antenna, comprising:

a plurality of inflatable, substantially spherical shells interconnected in fixed concentrically spaced relation;

each of said shells having a plurality of conductive antenna elements thereon;

said elements being aligned in radially stacked arrays each including an inner reflector element, an intermediate driven element and at least one outwardly disposed director element;

and switch means connected to said driven elements and being operable to interconnectselected elements.

5. An antenna, comprising;

a plurality of inflatable, substantially spherical shells interconnected in concentrically spaced relation;

each of said shells having a plurality of conductive antenna elements thereon; each of said elements being a substantially spiral dipole; said elements being aligned in radially stacked arrays each including an inner reflector element, an intermediate driven element and at least one outwardly disposed director element;

and switch means connected to said driven elements and being operable to interconnect selected elements.

6. An antenna, comprising:

a plurality of inflatable, substantially spherical shells interconnected in fixed concentrically spaced relation;

each of said shells having a plurality of conductive antenna elements thereon;

said elements being aligned in radially stacked arrays each including an inner reflector element, an intermediate driven element and at least one outwardly disposed director element;

said shells being of thin, flexible material;

and flexible webs interconnecting and spacing said shells when inflated.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Airborne Spiral Antennas, Minimize Drag, by Philip Klass; Aviation Week, July 14, 1958 (pages 75, 77, 79, 81, 82). 

6. AN ANTENNA, COMPRISING: A PLURALITY OF INFLATABLE, SUBSTANTIALLY SPHERICAL SHELLS INTERCONNECTED IN FIXED CONCENTRICALLY SPACED RELATION; EACH OF SAID SHELLS HAVING A PLURALITY OF CONDUCTIVE ANTENNA ELEMENTS THEREON; SAID ELEMENTS BEING ALIGNED IN RADIALLY STACKED ARRAYS EACH INCLUDING AN INNER REFLECTOR ELEMENT, AN INTERMEDIATE DRIVEN ELEMENT AND AT LEAST ONE OUTWARDLY DISPOSED DIRECTOR ELEMENT; SAID SHELLS BEING OF THIN, FLEXIBLE MATERIAL; AND FLEXIBLE WEBS INTERCONNECTING AND SPACING SAID SHELLS WHEN INFLATED. 